Process of treating sludge



K. IMHUFF AND H. BLUNK.

PROCESS OF TREATING SLUDGE.

APPLICATION FILED APR. 19, I913- Patented Dec 6, 1921b.

M m w sition.

UNITED STATES .PATEN rnocnss or rnnnrmesterner.

Specification of Letters Patent.

Patented en a, rat.

Application filed April to, 1913. Serial No. 7623M.

(GRANTED UNDER THE PROVISIONS 03' TM ACT OF MARCH. 3, 19211, d1 STAT. 1b., 11313.)

f 0 all whom it may concern Be it known that we, KARL IMHOFF and HEINRICH BLUNK, citizens of the German Empire, residing in Essen-on-t-he-Ruhr, in said German Empire, have invented certain new and useful Improvements in Processes of Treating Slud .e, (for which we have obtained patent in ermany, No. 275,498, June 17,1914,) of which the following is a specification.

The invention relates to an improved process for treating sludge and rendering it odorless for further disposition.

hen sewage material such as putrescible sludge, which usually has a high moisture content, or municipal sewage, which is also included under the term, is allowed to remain for tainer, various kinds of taking place. The two most important classes, of decomposition which take place may be termed putrid decomposition, which is characterized by the evolution of hydrogen sulfid and other bad-smelling gases, and odorless decomposition, in which practically only odorless gases (mainly marsh gas and carbon dioxid) are evolved.

Udorless decomposition possesses many advantages compared with putrid decompolBad-smelling odors are avoided near the sludge-containers and the sludge drying beds, and the sludge attains more some time in a condecompositmn are rapidly a consistency favorable to drying and subsequent handling.

The object of'the present invention is to suppress, by means of suitable processes, as

' far as possible the occurrence of putrid docomposition, and to so promote the biological changes of odorless decomposition as to ob tain properly decomposed sludge in the shortest possible time and in the smallest space. t V

To 'a certain extent, and under certain conditions, it, is possible to obtain in the sopalled Tmhofl-tanks (a combination of sedimentation-and decomposition chambers) a fairly odorless and a fairly rapid decomposition. All attempts have been in vain, h0wever, to'attain this rapid and odorless decomposition in ordinary sludge-containers ,of food in the sewage material,

The reason for this isthat it has been neglected to promote odorless decomposition. place, in deposited time, to a sufi which begins to take sludge after a certain cient extent by the addition form of fresh sludge. Another reason is that it has been neglected to permeate the fresh sludge sufficiently early with the exciters of odorless decomposition, so as to prevent the occurrence of putrid decomposition.

Both errors may be avoided when in a rlpened decomposltlon-chamber a continuous and lntilnate contact between fresh and decomposed sludge is secured. All of the following processes have this object as their aim. These processes render a rapid odorless decomposition possible in ordinary sludge-containers. They have the property I also, however, of accelerating decomposition in the Tmhofi-tanks.

It will be evident that the pumping of fresh sludge into one side of a. decomposition-chamber, which is the usual method, would militate against this fundamental principle. In this manner a pile of fresh sludge remains which would develop decomposition processes within itself, and upon which the exciters of odorless decomposition, which may be performing their work satisfactorily in other parts of the tank, can have no influence.

A marked improvement, however, is obtained if fresh sludge is conveyed simultaneously or successively to many points in the decomposition-chamber. Fixed or movable distribution-apparatus suited to this purpose is 'known.

Tn the accompanying drawings,

Figure 1 represents a vertical longitudinal section of an apparatus for treating sludge according to our improved process, and

Fig. 2 is a similar section of a modified construction of the same.

Similar letters of reference indicate corresponding parts in the figures of the draw- 111$.

f1 eferring to Fig. 1, or represents a settling chamber from whose floor sludge is removed from time to time by means of a pump h and at long intervals, but supplying it to the sludge-container at a uniform rate adapted to the decomposition-process. For this purpose an equalizing chamber f, connected with pump 6 by a pipe 6 with an adjustable discharge-apparatus may be located above the sludge-container. Compressed air may be forced in through the pipe 6, having perforations in its sides by the pump g, to agitate the sludge.

In order to insure from the outset the intimate mixture of the fresh and decomposing sludge, the fresh sludge may be conveyed to the sludge-chamber in the same pipe witha stream of decomposing sludge. This may, for example, be accomplished in the manner shown in Fig. 2. While pump 6 is pumping fresh sludge into the sludge-chamber, a second pump 9 is simultaneously lifting decomposed sludge through the pipe h and.

' pumping it uniformly with the fresh sludge through said pipe into the sludge-chamber. The pipe .71 through which the fresh sewage material and the decomposed sewage material is pumped into the container, is above the level of the sludge, which has been precipitated or settled from the liquid. An overflow pipe e performs the same function as in the embodiment shown in Fig. 1. In this manner an intimate and uniform mixture of both kinds of sludges is obtained.

In the sludge-chamber itself the intimate contact of fresh and decomposed sludge may be facilitated by simple devices. A large 1 part of the sludge in the sludge-chamber is kept in a continuous vertical motion during decomposition by the rising gas-bubbles. The inclined walls (Fig. 1) lead the sinking sludge to. any place where the mixture may be desired, for exam 1e to the place where the fresh sludge is lntroduced, near the triangular deflector 70 located at the lower end of the walls k. 7

Below the deflector k are inclined walls Z, which have an opening at their upper end for gathering the rising gas-bubbles and leading them to places where their stirring action may be most effective.

The upward motion of the gases causes in a short time the formation of a layer of I floating sludge which under certain condi- 'tions would continually increase in thickness.

Such sludge-particles as are entrained in this floating sludge, ifthey are not yet sufliciently decomposed, are no longer surrounded by as favorable conditions for decomposition as the other particles ofi decomposing sludge. The promotion of odorless decomposition makes it desirable that the floating sludge be caused to sink and distribute itself as soon as possible. For this purpose the walls I: are of advantage as they lead the rising gasbubbles away from the greater portion of the floating sludge and conduct them to isolated places where the may easily emerge. The floating sludge is thereby freed from the upward impulse of the continually rising gas-bubbles, the entrained gas soon esca es, and the floating sludge sinks.

e claim:

1. The process herein described of decomposing sludge, which consists in bringing decomposing sludge into intimate contact with fresh sludge.

2. The process herein described of decomposing sludge, which consists in bringing decomposing sludge simultaneously or successively into intimate contact with quantities of fresh sludge.

3. The process herein described of decomposing sludge, which consists in conveying fresh sludge in a continuous stream into intimate contact and admixture with decomposing sludge.

4:. The process herein described of decomposing sludge, which consists in conveying frseh sludge into decomposing sludge and intimately mixing the two kinds of sludge for producing odorless sludge.

5. The process herein described of decomposing sludge, which consists in conveying a stream of decomposing sludge which is fed simultaneously with fresh sludge and intimately intermingled therewith.

6. The process herein'described of decomposing sewage material which consists in bringing decomposing sewage material into intimate contact with fresh sewage material.

7. The process herein described of decomposing sludge which consists in bringing do simultaneously with fresh sewage material and intimately intermingled therewith.

10. The process herein described of decomposing sewage material which consists in conveying fresh sewage material in a 0011- In testimony, that we claim the foregoing tlnuous stream into intimate contact and adlas our lnvention, we have signedl our names it mlxture with decomposing sewage material. in presence of two subsorlhing witnesses.

11. The process herein described of decom- KARL lUFlE. [L s] 5 posing sludge which consists in conveying l-lElNlRlCl-l BLUN. [1,. a] fresh sewage material in a'continuous stream Witnesses: into intimate contact and admixture with HELEN Norm,

decomposing sluclge. Jones l nsru 

